The present invention relates to thermal printing postage meter.
It is an object of a conventional printing press type postage meters to print a postage indicia on a present envelope characterized by producing a postage indicia of consistent print contrast across the printed indicia. Additionally, it is an objective of a conventional printing press type postage meter to obtain suitable print quality in the specified printing area for envelope of varying paper grades (i.e., smoothness), porosity and envelope contour in the printing area.
Of particular note is the effect of the envelope contour in the printing area on print quality. It is a requirement, for example, by the United States Postal Service, that the postage indicia be printed in the upper right corner of the envelope. The contents of a particular envelope can cause this area to assume a variety of contour characteristic due in large part to the thickness of the contents and the particular shape of the contents.
Conventional thermal printers have required a relatively flat surface in the print area in order to insure adequate print quality. Also, sufficient time must be allowed for ink transfer which is a function of the smoothness and porosity of the printing media. Hence, the difficulty in applying thermal printing technics to postage metering mailing machine and like applications. That is, in order to obtain suitable print quality, the conventional thermal printing postage meter requires that the envelope characteristic be within a narrow range. As a result conventional thermal printing postage meters have not been able to adequately provide a printed postage indicia on an envelope having the requisite print quality over a preferred range of envelope paper smoothness, porosity and contours at desired speeds suitable for board postage metering mail applications.